I have no idea why, but Align seems to disable my ability to change transparency settings for borders and backgrounds in both Stuf and PB4. They work fine without align, and when I enable align they cannot be changed.

This would provide a white background behind the grid making it much easier to see the grid and UI element edges on busy or dark backgrounds. Basically white-out the world frame so you don't have to look around Orgrimmar or Stormwind for a patch of bright colors to stare at while you fiddle with your UI.